A Kill Switch For Genetically Modified Algae

By preventing bioengineered microalgae from growing outside the lab, researchers have reduced the risk of the genetically modified organisms escaping into the wild.

AsianScientist (Dec. 12, 2018) – Researchers at Hiroshima University, Japan, have developed a biocontainment strategy for genetically modified microalgae. They published their findings in ACS Synthetic Biology.

Bioengineered microbes could be useful in a wide variety of contexts, including agriculture and energy production. Engineered microalgae, for example, can help clean up oil refinery wastewater and function as a source of biofuel. However, like many other genetically modified organisms (GMOs), the safety of engineered microalgae is uncertain.

In the present study, scientists led by Associate Professor Ryuichi Hirota of Hiroshima University have devised a method to ensure that bioengineered microalgae are unable to survive outside the laboratory. They achieved this by making the microalgae reliant on phosphite—a nutrient source not found in the natural environment of microalgae.

At the core of phosphite is phosphorus, a crucial element in living things. Phosphorus also makes up a different molecule called phosphate, which organisms require to synthesize DNA and the intracellular energy currency molecule ATP.

Some microbes are able to convert phosphite into phosphate using an enzyme called phosphite dehydrogenase. By taking advantage of this enzyme and shutting down phosphate transporters in microalgae, Hirota and colleagues were able to make bioengineered microalgae survive only under lab conditions when phosphite is artificially supplied.

They further showed that the escape frequency of the bioengineered microalgae was at least three magnitudes lower than National Institutes of Health laboratory standards, which dictate that there should be less than one mutant cell per 100 million normal cells. Going forward, the researchers intend to test the strain in an artificial pond.

“Using GMOs is a balance of risk and benefit,” said Hirota. “They have potential, but at the same time, they pose a health risk… We need to develop such biosafety systems so we can study GMOs more responsibly.”



The article can be found at: Motomura et al. (2018) Synthetic Phosphorus Metabolic Pathway for Biosafety and Contamination Management of Cyanobacterial Cultivation.

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Source: Hiroshima University; Photo: Shutterstock.
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